There are many occasions where it is necessary or convenient for a person to sleep while in a sitting position. For example, such occasions arise during air travel on long-duration flights where there is no opportunity to sleep in a prone position. When sleeping in these circumstances it is common for a person's head to abruptly nod forward, generally awakening the person or at least disrupting the soundness of the person's sleep. Various pillows and neck braces have been developed in attempts to support a person's head while sleeping in a sitting position, but such devices are typically either very uncomfortable to wear or do not prevent abrupt forward nodding. What are needed therefore are devices for facilitating sleeping by a person who is sitting substantially upright.